The present invention relates to drip irrigation devices, and particularly to drip irrigation hoses used for discharging the irrigation water at slow rates from a plurality of longitudinally-spaced locations along the length of the hose. The invention also relates to flow-control elements for producing such hoses.
Drip irrigation hoses are increasingly being used for irrigating various types of plants since, among other advantages; they supply the water directly to the root regions of the plants and are therefore highly conservative of water and fertilizer. One type of drip irrigation hose includes a tube for conducting pressurized water through its interior and formed with a plurality of tube outlets for discharging the water at longitudinally-spaced locations along its length, and a plurality of flow-control elements fixed with respect to the inner surface of the tube to define a plurality of labyrinths, each having an inlet at one end communicating with the interior of the tube and an outlet at the opposite end communicating with the tube outlet for discharging water there from at a slow rate.
One problem in using drip irrigation hoses is the difficulty in ensuring relatively uniform discharge rates along the length of the hose. This problem is particularly acute where extremely long lengths of the hose are used since the hose itself produces a pressure drop along its length tending to decrease the discharge rate at the end of the hose. This sensitivity of discharge rate to the water pressure is also a problem where the land being irrigated is not flat and even.
Another problem with such drip irrigation hoses is sensitivity to clogging, and the difficulty in removing clogging particles.
In addition, such drip irrigation hoses are frequently used for only a single season, or for relatively few seasons; and accordingly the cost involved in producing such drip irrigation is a significant factor in their use.
Examples of how these problems have been addressed in the prior art are described in U.S. Pat. Nos. 5,333,793, 5,829,685, 5,615,838 and 6,736,337; in Publication No. US2003/0150940A1, published Aug. 14, 2003; and in International Patent Applications PCT/IL/97/00298 (International Publication No. WO/98/10625), PCT/IL01/00751 and PCT/IL02/00953. However, efforts are continually being made to improve the construction of such drip irrigation hoses with respect to one or more of the above problems.